From c6b07ad816e52ee6036d22931c952ceea3b0b5bc Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 19 Feb 2022 19:05:59 -0800
Subject: [PATCH] Fix cancelling ProjectileHitEvent for piercing arrows

Piercing arrows search for multiple entities inside a while
loop that is checking the projectile entity's removed state.
If the hit event is cancelled on the first entity, the event will
be called over and over again inside that while loop until the event
is not cancelled. The solution here, is to make use of an
already-existing field on AbstractArrow for tracking entities hit by
piercing arrows to avoid duplicate damage being applied.

== AT ==
protected net.minecraft.world.entity.projectile.Projectile hitCancelled
---
 .../projectile/AbstractArrow.java.patch       | 42 ++++++++++++++-----
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/paper-server/patches/sources/net/minecraft/world/entity/projectile/AbstractArrow.java.patch b/paper-server/patches/sources/net/minecraft/world/entity/projectile/AbstractArrow.java.patch
index b4f04e3bf6..c09d1374fb 100644
--- a/paper-server/patches/sources/net/minecraft/world/entity/projectile/AbstractArrow.java.patch
+++ b/paper-server/patches/sources/net/minecraft/world/entity/projectile/AbstractArrow.java.patch
@@ -115,7 +115,29 @@
  
                      this.hasImpulse = true;
                      if (this.getPierceLevel() > 0 && projectiledeflection == ProjectileDeflection.NONE) {
-@@ -356,8 +381,8 @@
+@@ -317,8 +342,21 @@
+ 
+             this.level().addParticle(ParticleTypes.BUBBLE, pos.x - vec3d1.x * 0.25D, pos.y - vec3d1.y * 0.25D, pos.z - vec3d1.z * 0.25D, vec3d1.x, vec3d1.y, vec3d1.z);
+         }
++
++    }
+ 
++    // Paper start - Fix cancelling ProjectileHitEvent for piercing arrows
++    @Override
++    public ProjectileDeflection preHitTargetOrDeflectSelf(HitResult hitResult) {
++        if (hitResult instanceof EntityHitResult entityHitResult && this.hitCancelled && this.getPierceLevel() > 0) {
++            if (this.piercingIgnoreEntityIds == null) {
++                this.piercingIgnoreEntityIds = new IntOpenHashSet(5);
++            }
++            this.piercingIgnoreEntityIds.add(entityHitResult.getEntity().getId());
++        }
++        return super.preHitTargetOrDeflectSelf(hitResult);
+     }
++    // Paper end - Fix cancelling ProjectileHitEvent for piercing arrows
+ 
+     @Override
+     protected double getDefaultGravity() {
+@@ -356,8 +394,8 @@
  
      protected void tickDespawn() {
          ++this.life;
@@ -126,7 +148,7 @@
          }
  
      }
-@@ -386,9 +411,9 @@
+@@ -386,9 +424,9 @@
      }
  
      @Override
@@ -138,7 +160,7 @@
          }
      }
  
-@@ -423,7 +448,7 @@
+@@ -423,7 +461,7 @@
              }
  
              if (this.piercingIgnoreEntityIds.size() >= this.getPierceLevel() + 1) {
@@ -147,7 +169,7 @@
                  return;
              }
  
-@@ -440,11 +465,18 @@
+@@ -440,11 +478,18 @@
              entityliving.setLastHurtMob(entity);
          }
  
@@ -167,7 +189,7 @@
          }
  
          if (entity.hurtOrSimulate(damagesource, (float) i)) {
-@@ -490,7 +522,7 @@
+@@ -490,7 +535,7 @@
  
              this.playSound(this.soundEvent, 1.0F, 1.2F / (this.random.nextFloat() * 0.2F + 0.9F));
              if (this.getPierceLevel() <= 0) {
@@ -176,7 +198,7 @@
              }
          } else {
              entity.setRemainingFireTicks(k);
-@@ -506,7 +538,7 @@
+@@ -506,7 +551,7 @@
                          this.spawnAtLocation(worldserver2, this.getPickupItem(), 0.1F);
                      }
  
@@ -185,7 +207,7 @@
                  }
              }
          }
-@@ -538,7 +570,7 @@
+@@ -538,7 +583,7 @@
              Vec3 vec3d = this.getDeltaMovement().multiply(1.0D, 0.0D, 1.0D).normalize().scale(d0 * 0.6D * d1);
  
              if (vec3d.lengthSqr() > 0.0D) {
@@ -194,7 +216,7 @@
              }
          }
  
-@@ -675,7 +707,7 @@
+@@ -675,7 +720,7 @@
          }
  
          if (nbt.contains("weapon", 10)) {
@@ -203,7 +225,7 @@
          } else {
              this.firedFromWeapon = null;
          }
-@@ -688,34 +720,31 @@
+@@ -688,34 +733,31 @@
          Entity entity1 = entity;
          byte b0 = 0;
  
@@ -250,7 +272,7 @@
          }
  
          this.pickup = entityarrow_pickupstatus;
-@@ -724,9 +753,24 @@
+@@ -724,9 +766,24 @@
      @Override
      public void playerTouch(Player player) {
          if (!this.level().isClientSide && (this.isInGround() || this.isNoPhysics()) && this.shakeTime <= 0) {